1. Field of the Invention
The present invention relates to an apparatus and a method for synthesizing a musical instrument digital interface (MIDI), and more particularly, to an apparatus and a method for synthesizing a MIDI that is based on a wave table and is capable of compressing and storing sound samples of one or more instruments in the wave table.
2. Description of the Related Art
A MIDI is a standard protocol for data communication between electronic musical instruments. The MIDI is a standard specification for hardware and data structures that provide compatibility between inputs and outputs of musical instruments or between musical instruments and computers through a digital interface. Accordingly, devices having the MIDI can share information because the data created are compatible.
The MIDI contains information regarding how instrument sounds should be expressed as well as basic musical information such as the type of instruments producing sounds, a tone level, and a tone length.
Methods for synthesizing a real sound using a multimedia device on the basis of musical information are roughly divided into a frequency modulation (FM) type method and a wave table type method.
The FM type method extracts frequency information related to a sound that a specific musical instrument should produce and generates signals for the frequency when synthesizing a sound. However, the FM type method is limited to generating certain sounds and the generated sound is quite different from the real sound.
To overcome these disadvantages, a method for recording a real sound and using the recorded sound as a sound source has been developed; wave table type method. The wave table type method obtains and stores samples of sounds actually played for each musical instrument in advance and processes a specific instrument's stored sound samples according to musical information included in a MIDI file in order to synthesize a sound.
Processing stored sound samples according to the musical information contained in the MIDI file to synthesize a sound is generally referred to as MIDI synthesis. Therefore, processing stored sound samples according to the musical information contained in a MIDI file stored in a wave table in order to synthesize a sound is referred to as MIDI synthesis based on a wave table.
When synthesizing a MIDI using the wave table type method, samples of a sound actually played for each instrument are used. Therefore, a tone level is modulated, a tone length is changed, and a tone expression is applied on the basis of musical information described in the MIDI file, thereby producing a sound.
When an instrument's sound samples are obtained and stored in the wave table, articulation data such as variations of the sample sounds in time and fine variations of a frequency are additionally stored. When a sound is synthesized, the articulation data is utilized so that a sound is properly produced.
The wave table used in MIDI synthesis has a predetermined type so as to maintain compatibility between many synthesis apparatus. A downloadable sound (DLS) type is generally used.
A wave table storage format of the DLS type prescribes in what form information of an instrument's sound samples and articulation data are stored. Specifically, the wave table storage format of the DLS type prescribes that an instrument's sound samples are stored in a wave format, which is an audio-data-storing format.
As described above, the conventional wave table type MIDI synthesis method requires that an instrument's sound samples actually be played, thereby requiring a large storage space. The wave table type method requires fewer operations than the FM type synthesis method but requires more storage space in synthesizing a sound. Therefore, it is difficult to perform a MIDI synthesis in a small apparatus having limited storage space.
There is a need for a MIDI synthesis operation and method that is adaptable to a small apparatus leaving limited storage space. The present invention addresses these and other needs.